Sources and biodegradability of dissolved organic matter in two headwater peatland catchments at the Marcell Experimental Forest, northern Minnesota, USA

Stephen D. Sebestyen, Meghan Funke, James B. Cotner

Research output: Contribution to journalArticlepeer-review

Abstract

Where they are present in catchments, peatlands are a dominant source of dissolved organic matter (DOM) to surrounding waterways due, in part, to high production rates. Despite the preponderance of peatlands in northern latitudes and expected peatland vulnerability to climate change, little is known about peatland DOM degradation relative to a more comprehensive understanding of degradation when DOM is sourced from upland-dominated catchments. We compared DOM biodegradability of various sources of stream water in two catchments having peatlands (22%–33% of the area) surrounded by upland forests (70%–90% of the area, either deciduous or coniferous). We measured total organic carbon (TOC), and biodegradable dissolved organic carbon concentrations; bacterial respiration rates; streamflow; and upland runoff during and after snowmelt (March to June, 2009–2011). We also explored if DOM in upland runoff stimulated biodegradation of peatland-derived DOM (i.e., a priming effect), and if forest cover type affected DOM biodegradability. As expected, the peatlands were the largest sources of both water (72%–80%) and TOC (92%–96%) to the streams although more area in each catchment was in uplands (70%–90%). Several results were unexpected, yet revealing: (1) DOM from peatlands sometimes had the same biodegradability as DOM from uplands, (2) upland sources of DOM had negligible effects on biodegradability in the peatland and downstream, and (3) upland deciduous cover did not yield more degradable DOM than conifer cover. The most pronounced effect of upland runoff was dilution of downstream TOC concentrations when there was upland runoff. Overall, the effects of upland DOM may have been negligible due to the overriding effect of the large amount of biodegradable DOM that originated in bogs. This research highlights that peatland-sourced DOM has important effects on downstream DOM biodegradability even in catchments where upland area is substantially larger than peatland area.

Original languageEnglish (US)
Article numbere14049
JournalHydrological Processes
Volume35
Issue number2
DOIs
StatePublished - Feb 2021

Bibliographical note

Funding Information:
The Northern Research Station (NRS) of USDA Forest Service funded this research, long‐term monitoring at the Marcell Experimental Forest, analyses done in the Forestry Sciences Lab, and contributions of S.D.S., hydrological technicians (C. Dorrance, D. Kyllander, J. Prososki, M. Old, M. Wiley), administrative staff (A. Girtz), students (K.F. Watson), and lab staff (J. Larson, K. Oleheiser, D. Nelson) to the project. M.F. was supported by a Rothman Fellowship, a Dayton Fund Fellowship, and National Science Foundation (NSF) Integrative Graduate Education and Research Traineeship Funds (DGE‐0504195). J.B.C. was partially supported through a NSF Division of Integrative Organismal Systems (IOS) award 1257571. R.K. Kolka (USDA Forest Service) provided logistical support. A. Little and K. Wolfe processed samples in the University of Minnesota Aquatic Ecology Laboratory. J.D. Jeremiasion (Gustavus Adolphus College) and his undergraduate students collected some of the lagg water samples. B.H. Hill (USEPA, Duluth, MN, retired) provided estimates of bog and lagg areas for the S6 catchment. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the US Government.

Funding Information:
The Northern Research Station (NRS) of USDA Forest Service funded this research, long-term monitoring at the Marcell Experimental Forest, analyses done in the Forestry Sciences Lab, and contributions of S.D.S., hydrological technicians (C. Dorrance, D. Kyllander, J. Prososki, M. Old, M. Wiley), administrative staff (A. Girtz), students (K.F. Watson), and lab staff (J. Larson, K. Oleheiser, D. Nelson) to the project. M.F. was supported by a Rothman Fellowship, a Dayton Fund Fellowship, and National Science Foundation (NSF) Integrative Graduate Education and Research Traineeship Funds (DGE-0504195). J.B.C. was partially supported through a NSF Division of Integrative Organismal Systems (IOS) award 1257571. R.K. Kolka (USDA Forest Service) provided logistical support. A. Little and K. Wolfe processed samples in the University of Minnesota Aquatic Ecology Laboratory. J.D. Jeremiasion (Gustavus Adolphus College) and his undergraduate students collected some of the lagg water samples. B.H. Hill (USEPA, Duluth, MN, retired) provided estimates of bog and lagg areas for the S6 catchment. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the US Government.

Publisher Copyright:
© 2021 John Wiley & Sons Ltd

Keywords

  • bog hydrology
  • dissolved organic matter
  • DOM biodegradability
  • DOM sources
  • northern peatlands
  • source areas in upland-peatland catchments
  • upland forest

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